Capillary Mounting HardwareMounting a Capillary Thermostat doesn’t need to be difficult. The first step is to make sure you know what type of Capillary Thermostat you’ll need. These aspects include the type of bulb and capillary tubing.

More Information about Capillary Switches

There are a number of elements that go into designing a bulb and capillary thermostat switch. The most important elements are bulb diameter and length restrictions, capillary tube length, and switching temperature.

Bulb diameter and length restrictions

When designing a bulb certain size or volume requirements must be considered. When there is a restriction on length then outside diameters may need to be changed. When retrofitting an existing Capillary Switch, restrictions on the thermowell or chamber may control the size.

Capillary tube length

The location of the switch and the distance away from the bulb will give you the capillary tube length. Always leave extra room on your tube length it can be easily coiled and out of the way. Some switches or Probes have no Capillary tube the switch is mounted directly to the bulb. Avoid sharp edges and tight bends a tube can be crimped off.

Switching Temperature

Bulb placement is important. Do not get too close to heaters or chillers as the sensing probe will get a false temperature reading. Center of the fluid (or Gas) mass is always best. If unknown, it may work best if we build you a switch that is adjustable and send it to you for adjustment and return it for accurate calibration temperatures.

Not all Bulbs, Probes and Capillary Tubes use a fluid fill, some use a gas. There are a large number of different fluids and gases that are used. This is based on:

  • What material is being sensed for temperature
  • Temperature range of the switch
  • Other external requirements to the switch

Other engineering and design requirements are also taken into account when a fill material is chosen. A large number of capillary tubes use a variation of an alcohol fill. Some even have odors added so a leak can be detected. For help on a specific application, contact one of our customer service representatives at the link below.

Now that you know which thermostat you need, we can get to mounting it. The Senasys Thermostats are available with a bottom mounting bracket that is assembled to the switch, or upon installation. To assemble the bottom bracket hardware to a capillary thermostat, follow the simple instructions.

  1. Mount the spacer over the screws
  2. Place bracket over spacer
  3. Use small amount of loctite and tighten screws. Try not to rotate the screws in the chasis as it can slightly change the calibration of the switch.

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Bulb & Capillary Thermostats

Original equipment manufacturers worldwide use thermostat switches designed and manufactured by STEMCO, a Division of Senasys. No matter which style or model you choose, all of the capillary thermostat switches operate using the same physics. A fluid is encapsulated in a metal and when the temperature changes the fluid either expands or contracts. This fluid change moves a diaphragm which is in touch with a snap action switch and either opens or closes a circuit.

Ambient Compensation

Our capillary thermostats can be ambient compensated to offset the differential in temperature which keeps our thermostat controls more accurate as it’s environment changes.

Custom Options

Capillary thermostat switches built by Senasys can also be built to customer specifications. This insures you get the exact control you want without paying for features you don’t need.